1. Field of the Invention
This invention relates to a motor vehicle lock having mechanical components, such as a lock latch, detent pawl, inside and outside actuation lever, and inside and outside safety lever. Today, motor vehicle locks increasingly include electrical or electronic components, such as electrical actuators and especially sensors for monitoring the current state of the motor vehicle lock mechanism.
2. Description of Related Art
When a sensor delivers information about the current state of a motor vehicle lock mechanism, such as the adjustment motion or the current position of individual force application components which accommodate the actuating force and motion to be applied to the lock mechanism, the sensor relays the information to other mechanical components of the lock mechanism. One element of a motor vehicle lock mechanism which can be monitored is a nut of the lock mechanism which in a certain situations acts on the outside safety lever. This nut is essentially cylindrical and can be turned around an axis of rotation.
In such a lock mechanism, the position of the nut of the lock is detected via a measurement system which preferably includes a sensor as well as a measurement element. Depending on the sensor, the location of the measurement element can be detected within certain limits. That is, in order for the position detection of the measurement element by the sensor to take place, it is necessary for the measurement element to be located at least partially within the measurement range of the sensor. For a measurement systems based upon the Hall effect, the sensor is a Hall sensor chip and the measurement element is a component which bears a magnet or include at least in part a magnetized material.
A similar arrangement is shown in published German Patent Application DE 37 17 778 A1 which illustrates that a nut of the lock mechanism is dynamically coupled to a disk-shaped intermediate element. The two components, the nut of the lock and the intermediate element, can be turned around the same axis of rotation. The intermediate element together with the nut of the lock ensures dynamic coupling between the paddle and the outside safety lever of the motor vehicle lock and therefore also assumes the function of the measurement element. To monitor the angular position of the nut of the lock a microswitch, which is the sensor of the measurement system, is provided directly on the intermediate element in a radial alignment. The intermediate element in an edge-side area has a crank which enables the microswitch to roughly detect the position of the nut of the lock.
It is particularly noted that the intermediate element of this design is made as a component which is separate from the nut of the lock so that these two components can be configured independently of one another within certain limits. This is consistent with the prerequisite for the modularization of components which seems always to be necessary in the automobile industry. The disadvantage of this approach, however, is that this arrangement of an intermediate element and a nut requires a relatively large amount of installation space due to the disk-shaped intermediate element. Additionally, the installation cost is relatively high due to the additional componentxe2x80x94the intermediate element, and, finally, the tactile sensor principle is fault-susceptible and is subject to high wear.
There are presently other alternatives to tactile measurement, such as optical, electrical and magnetic measurement processes.
One such approach, which is based on the principle of inductive sensing, is illustrated in German Patent DE 39 41 086 C2. In this approach, strips of a magnetic material, which influence a magnetic circuit, are applied to the outside cylindrical surface of the nut of the lock mechanism and are a part of the measurement element. When the nut of the lock is turned, the strips are guided past an inductive sensor. With this arrangement, the strips can be provided in several tracks such that the position of the nut of the lock can be determined based on the inductive sensor signals. This simple approach which can be implemented with little effort, however, has the disadvantage that the nut of the lock must have an essentially planar surface. Furthermore, depending on the material of the nut of the lock, the adhesion of the strips to the nut surface can be a problem. Finally, with this approach, the nut of the lock cannot be metallic, since there would not be sufficient resolution of the measurement signal from the strips.
In the automobile industry, Hall sensors have become common in the field of motor vehicle locks. These sensors offer not only high reliability and reasonable price, but also provide highly accurate measurements.
One approach for the xe2x80x9ccontactlessxe2x80x9d determination of the angular position of the nut of the lock is illustrated in German Utility Model DE 296 18 688 U1. The underlying the principle of the Hall effect on this approach is already known. Here, a magnet is countersunk into the non-ferromagnetic wall of the nut of the lock. The non-ferromagnetic wall of the nut together with the integrated magnet represents a measurement element. When the nut of the lock turns, the embedded magnet is guided through the measurement area of the Hall sensor chip. This approach, like previously discussed constructions, presupposes that the nut of the lock consists of plastic or the like. Furthermore, the structural design of the nut is greatly limited by the fact that the magnet is countersunk into the wall of the nut of the lock.
In summary, the two known approaches to xe2x80x9ccontactlessxe2x80x9d detection of the position of the nut of a lock in the prior art are associated with disadvantages. Further, a modular concept for either approach cannot easily be implemented due the structural configuration of the nut of the lock being limited by the attachment of the magnetic material or a material which influences the magnetic circuit. However, in the automobile industry the ability to provide configurations which maximize the modular concept in order to meet a client wishes is paramount. That is, any new product line must be able to be combined with a combination of suitable standard components.
Therefore, an object of the invention is to improve the known motor vehicle lock detailed above such that xe2x80x9ccontactlessxe2x80x9d monitoring of the angular position of the nut of the lock becomes possible in a particularly compact manner while maintaining the required modular capability.
This object is achieved in a motor vehicle lock of the present invention by taking several important design factors into consideration in the motor vehicle door lock.
First of all, the measurement element be located directly on the outside cylinder surface of the nut of the lock, but at the same time be made as a component which is separate from the nut. An annular configuration, or at least annular in certain sections, of the measurement element will ensure a high degree of modular compactness which will simultaneously enable a simple installation. With such a configuration, that is the separability of the nut and the measurement element, the modular structure of the overall system is maintained. Since none of the components of the measurement system are part of nut itself, the nut can be configured largely without limitation. Care must simply be taken that the separate measurement element can be attached to the nut of the lock.
In one embodiment, a single xe2x80x9cstandard nutxe2x80x9d can be provided which, depending on the product version and the sensor, can be combined with different measurement elements of the invention.
One particular advantage of the annular measurement element according to the invention arises in the ability to pre-assemble the components into position by injection-molding material onto the nut of the lock such a connecting bridge(s) between the nut of the lock and the measurement element is formed. The(se) connecting bridge(s) is fabricated as scored sites which break during installation. The measurement element can be moved into its final assembly position when the connecting bridge(s) is broken.
The aforementioned pre-assembly position of the measurement element can be anywhere on the nut of the lock. However, it is especially advantageous if the measurement element is aligned coaxially with the nut so that the measurement element can be moved into its final installation position by a single linear movement. In this embodiment, the measurement element can also be used as a centering aid when the nut of the lock is installed in the motor vehicle lock which reduces the installation cost.
The embodiments of the motor vehicle lock mechanism of the invention acquire a special importance when used conjunction with a measurement system employing a Hall sensor. That is, the measurement element is then preferably a plastic ring which holds one or more magnets. Therefore, as long as the mechanical orientation of the measurement element to the nut of the lock is kept constant, the structural configuration of the measurement element is optional. Furthermore, the annular measurement element of the invention can be easily replaced, if necessary, during a manufacturing shift which employs a new sensor or another evaluation process.